This invention relates to a new method construction of a bubble-driven ink jet print head which results in a monolithic structure.
The background with regard to bubble driven ink jet printing is adequately represented by co-pending U.S. application Ser. No. 292,841 by Vaught, et al., assigned to Hewlett-Packard Company, and by the following U.S. patents assigned to Canon Kabushiki Kaisha, Tokyo, Japan: U.S. Pat. Nos. 4,243,994; 4,296,421; 4,251,824; 4,313,124; 4,325,735; 4,330,787; 4,334,234; 4,335,389; 4,336,548; 4,338,611; 4,339,762; and 4,345,262. The basic concept there disclosed is a device having an ink-containing capillary, an orifice plate with an orifice for ejecting ink, and an ink heating mechanism, generally a resistor, in close proximity to the orifice. In operation, the ink heating mechanism is quickly heated, transferring a significant amount of energy to the ink, thereby vaporizing a small portion of the ink and producing a bubble in the capillary. This in turn creates a pressure wave which propels an ink droplet or droplets from the orifice onto a closeby writing surface. By controlling the energy transfer to the ink, the bubble quickly collapses before any ink vapor can escape from the orifice.
In each of the above-references, however, the print heads described consist of multiple part structures. For example, resistors are most often located on a substrate, and an orifice plate having accurately scribed ink capillaries must be attached to the substrate with great care to insure proper alignment of the resistors and ink capillaries. Generally, this attachment is performed by gluing, solder glass attachment, or anodic bonding. Such meticulous handling of multiple part assemblies adds greatly to the cost of production of such print heads.